[PATCH v1 1/5] drm/i915/gvt: GVTg handle enable_pvmmio PVINFO register

[Zhang, Xiaolin]

On 11/09/2018 10:48 AM, Zhenyu Wang wrote:
> On 2018.11.05 17:20:45 +0800, Xiaolin Zhang wrote:
>> implement enable_pvmmio PVINFO register handler in GVTg to
>> control different level pvmmio optimization within guest.
>>
>> report VGT_CAPS_PVMMIO capability in pvinfo page for guest.
>>
> Another thing that I think is not consistent for these pv interface
> which is the guest to host notification is not aligned, some are none
> e.g share page setup, master irq, some are implicitly through specific
> MMIO write, e.g execlist port. Which seems not good to me. We should
> have a formal notification definition for all of them e.g through
> current 'g2v' notification interface, looks ppgtt update uses that. So
> host would handle pv request when receiving notification consistently,
> instead of having different ways which is not good to track.
>
> Thanks

Thanks your point. the host to handle pv request is the same way just
with different names. Shared page setup is the foundation of PV features
and only setup once. so shared page setup must be setup first and for
this trap notification, we have created new shared_page_gpa register for
this purpose which should be notified  from guest. for master irq
feature, we crated one more register "check_pending_irq" for guest
notification to trap from guest to host; for workload submission
(execlist), we reuse the submit register to trap from guest to host
instead of creating new one to reduce trap cost (otherwise, we have 2
traps here , one for submit register and one for notification). for
ppgtt, since the existing g2v notification can't cover our requirement,
so we extended 3 more in G2V PPTT notification definition.  Maybe these
names (shared_page_gpa, check_pedning_irq, submit_reg) are not uniform,
but they do the same thing for g2v notification.

BRs. Xiaolin